I've had mixed luck with either steaming a vintage brush to loosen the knot or using a knife, drill, etc. to remove an old knot. Combination of bad luck with steaming and not the highest tool using skills on my part. I recently bought 4 vintage Ever Ready brushes on the "Bay and decided to put them in a large jar of water and let them soak to see if the knots loosen. I have 8 other brushes in my rotation, so I can wait a long time to see if the knots loosen. After about 2 weeks, the knots still weren't removable, so back in the water the brushes went. Anyone else have experience with soaking the knots loose? I'll report my progress.